The present invention is in the field of insect trapping. More specifically, the invention relates to a device and method for trapping insects which feed on mammalian blood.
Insects use their senses to search for food. A combination of chemical and physical factors whether by virtue of either their sheer existence or by their presence at a definite magnitude range are intercepted by the insect sensory organs to direct it towards the potential food source. Such factors that cause the insect to approach such a site will henceforth be referred to as attractants. A prominent attractant cited repeatedly in the literature is carbon dioxide (e.g. Edman, Orientation of some Florida mosquitoes towards small vertebrates and carbon dioxide in the field. Journal of Medical Entomology, 15:292-296, 1979). An organic molecule, 1-octen-3-ol is also potentially attractive to insects and mosquitoes, alone or in combination with other factors (e.g. Hall et al., 1-octen-3-ol: a potent olfactory stimulant and attractant for tsetse isolated from cattle odors, Insect Science and its Applications, 5:535-539, 1984).
Female mosquitoes need to consume a certain amount of mammalian blood in order to complete the breeding cycle and are therefore equipped with necessary facilities for accomplishing this task. In this context, female mosquitoes are provided with a potency to detect mammals, including humans. Mosquito bites are a source of great inconvenience and are also a disease transmission pathway and there is accordingly a constant search for effective ways to eliminate mosquitoes. Up to now there has not been found an efficient practical method of effectively eliminating this pest. One method of eliminating mosquitoes proposed in the past is by luring them into traps.
Several factors were shown previously to serve as attractants of insects in various kinds of traps. Such are, for example, carbon dioxide, octenol and animal odors (e.g. Becker et al., Medical and Veterinary Entomology, 9:377-380, 1995). Poultry protein was also proposed as a fly attractant together with microorganisms capable of digesting the protein (Andersen et al., U.S. Pat. No. 4,849,216). Another type of insect attractant proposed for use in traps comprising various other components is yeast together with a carbohydrate source which it is capable of fermenting (see for example, Bouillard, J., et al., in French Patent Publication FR 2705200). Dieguez, J. M., et al., in U.S. Pat. No. 5,382,422, describe a method for providing a flow of carbon dioxide gas containing a vapor of a liquid insect attractant selected from acetone and octanol. A trap for hematophagous insects utilizing a methanol fuel cell to provide carbon dioxide, water vapor and heat, as attractive agents, was proposed by Miller, M. H., in U.S. Pat. No. 5,669,176. Moreover, carbon dioxide for use as an insect attractant, was chemically generated in U.S. Pat. No. 4,506,473 (Waters, Jr., J. et al.).
The entire contents of the above-mentioned patents, patent applications and literature articles are incorporated by reference herein.
The present invention is based on the discovery that in a trapping device for insects which feed on mammalian blood, and which comprises a chemical attractant for the insects, significantly improved results are obtained by including in the device a physical attractant consisting of a heated dark panel, together with a trapping arrangement effective in trapping mosquitoes attracted to said panel.
More particularly, the invention provides a trapping device as aforesaid, comprising a combination of the dark panel; a source of said carbon dioxide for emitting the same in the vicinity of the panel, a heating source effective to heat the panel, and the trapping arrangement.
In a particular embodiment, the chemical attractant includes carbon dioxide. It is particularly preferred that at least one of the following features applies:
(a) the insects are mosquitoes;
(b) the trapping arrangement comprises an adhesive, preferably applied onto said panel;
(c) the panel is heated to a temperature of within the range of about 30 to 45xc2x0 C.;
(d) the source of carbon dioxide (when used) is a fermentation process involving the action of microorganisms, preferably comprising yeast, on a fermentable substrate in aqueous medium.
In another embodiment, the chemical attractant comprises at least one member selected from fermenting yeast, yeast extract, peptone, acetone, lactic acid and carbon dioxide.
Also provided by the invention is a method for trapping insects which feed on mammalian blood, which comprises use of a chemical attractant for the insects and which comprises use additionally of a physical attractant consisting of a heated dark panel, together with a trapping arrangement effective in trapping mosquitoes attracted to said panel.
The heating source typically heats the panel to a temperature within the range of 30-55xc2x0 C., e.g. about 30-45xc2x0 C., preferably within the range of about 33-41xc2x0 C., typically to a temperature of about 35-39xc2x0 C. In a particular embodiment, the panel is heated to a temperature of about 37xc2x0 C. In another preferred embodiment, the panel is heated to a temperature of about 40-44xc2x0 C.
As indicated above, the CO2 source, in accordance with an embodiment of the invention, is constituted by microorganisms (e.g. yeast) which are capable during fermentation, to emit carbon dioxide. Where yeast is used, this may be provided in a capsule, in dispersed form, as a hard-pressed tablet, etc. In order to effect fermentation, the microorganisms, e.g. the yeast, are brought into intimate contact with a fermentable substrate, such as sugar in aqueous medium. The microorganism may, for example, be included in a small vessel having an exhaust outlet at the vicinity of said panel.